Organic driers in organic film forming compositions



ORGANIC DRIERS 1N ORGANIC FILM FORMING COMPOSITIONS- No Drawing.Application September 5,

Serial No. 245,266

8- Claims. (Cl. 106-310) This invention relates to the employment of anovel class of compounds as replacements for the lead soaps normallyused as drier catalysts in drying oil containing coating compositions.

Heretofore, the oil-soluble salts of a variety of organic acids havebeen the principal siccative materials used as catalyst to promote thedrying of compositions containing unsaturated fatty acid groups. Thethree principal metal organic soaps employed are the lead, cobalt andmanganese salts of high molecular weight organic compounds, e. g.,rosinates, naphthenates and o'ilsolates or long chain fatty acid soaps.Other metals known to have some siccative eifect include iron, Zinc,calcium and nickel salts and soaps, but their use is more specific thanthe three principal metals named.

The three principal driers named are known to have an individual effectin drying oil fatty acid group containing coating compositions, and itis general practice to use the cobalt, lead and manganese salts or soapsin combination to avail of the individual stimulus to drying contributedby each metal present. I

It is fairly generally agreed in the art as to theory that the metallicsoaps function: (1) to shorten or eliminate the normal induction periodpreceding the observable drying character of the unsaturated oils, (2)to accelerate the absorption of oxygen by the drying oil, (3) to causegelation or solidification of the drying oil film at a lower totaloxygen absorption than in the absence of the metal drier, and (4) todecrease the amount of oxygen absorption over the maximum absorptionoccurring in the absence of metal driers. Briefly stated, the drying ofan oil film is believed to be initiated by oxidation and completed bypolymerization within the film, and that both types of reaction areaccelerated by the presence of metal driers.

The three principal metal driers are known to have. many objectionablecharacteristics including high consistency at high metal content,tendency to sludge out and tendency to increase viscosity upon age aftermanufacture.

However, the lead driers have certain objectionable qualities which areof a more serious nature. One printlip?% objection to lead driers is thetoxic quality of lead itse During the last several decades, attentionhas been focused upon the toxic quality of lead in paints by numerouscourt actions involving lead poisoning. It has been alleged thatchildren have become the victims of lead poisoning by chewing the paintofif their cribs, and

; cattle by a similar attack on fences and barns painted withlead-containing paints. As facturers of articles intended for toys andfurniture have insisted absolutely lead free. This was a difiicultrequirement as lead is considered almost essential to obtain throughdrynecessary to quality finishes.

Another objection to lead driers has been the uncertainty of behavior ofworld markets in relation to its price and availability. Particularlyduring war periods, availability of lead for peacetime requirementsbecomes a serious .problem.

Accordingly, we have directed our efforts toward purely organiccompounds containing no metals at all which might be useful to supplantlead entirely.

As a result of a research project undertaken with this yiew as a goal,we have discovered that not only can a result, many manuuse by childrenas in that such coatings be United States Patent 0 lead soaps beeliminated by substitution therefor of a particular class of purelyorganic compounds, but in several instances actual improvements insiccative behavior over the usual lead soaps has been obtained. It hasbeen further found that the substitutes for lead are more specific intheir catalytic effect than is lead, and while all function as driers ina particular system, one of the group hereinafter disclosed mayout-perform another. So far we have no full explanation for thisphenomenon but we believe that it may be related to the molecular weightof the given organic drier. Our present research was conducted purely ona weight for weight substitution basis and it is reasonable to assumethat slightly less amounts of some outstandingly useful compounds andslightly more of others in given formulations may result in greatereconomy in some cases and greater siccative quality in otherapplications, attention being given to molecular weights.

It is the broad object, therefore, to provide a drier catalyst for usein coating compositions containing drying oil fatty acid groups, saidcatalysts being purely organic in nature, having a similar behavior andfunction to metallic soaps presently employed as driers therein.

In general, this broad objective hasv been accomplished through the useof metal-free organic compounds containing from seven to eighteen carbonatoms and a carbonyl group, said compound selected from the classconsisting of aliphatic aldehydes wherein said substituent ischaracterized by the presence in said substituent of a carbonyl group.

The use of compounds other than the metal salts and soaps of highermolecular weight fatty acids has been priorly suggested. However, as faras the applicants are aware, the prior art has not been concerned withdriers for unsaturated drying oil fatty acid containing coatingcompositions to an appreciable extent. Hexa-substituted ethanes havebeen suggested as possible driers, and certain mercaptans have beenindicated as having an effect upon unsaturated maleic type resins.Cyanamide, acrylonitrile, guanyl urea compounds and lauro-guanamine havealso been priorly suggested.

In making the tests and comparisons for the purpose of this research,tests were carried out in an air-conditioned room where temperature,humidity and light conditions were kept quite constant.

As it is usually customary to employ lead driers in con unction withcobalt and manganese driers, the tests were further made upon the dryingoil containing compositions having present from 0.023% to 0.30% cobalt,based on the metal and the vehicle solids, and in man cases anadditional manganese salt present from 0.005% to 0.05% on the same oasisof calculation.

An additional control test was carried through simultaneously containingonly the metallic driers other than lead as a further means of of thenon-metallic organic compounds under test.

Comparative tests were conducted on identical vehicles, e. g., onealiquot portion of a selected vehicle would contain as an additive theconventional amount of the lead soap or drier and another aliquotportion or the same vehicle would carry an equivalent amount by weightto the lead soap of the purely organic compound under test.

the quantities of the purely organic compounds used in the tests rangedfrom 0.25 to 2.0% based on the total vehicle solids of the particulardrying oil containing vehicle tested. The preferred range or percentagewas found to be from 0.5% to 1.75% based on the said total vehiclesolids content of the coating.

A series of eight different qualities of coating vehicles containingdrying oil fatty acid groups were selected for the purpose of evaluationof the compounds tested. These vehicles contained from drying oil in theoutside house paint vehicle to as low as 32% of oil modification in oneof the alkyds employed. Six of the vehicles selected are furtherdescribed and identified in the table.

A number of the compounds tested were objectionable from a practicalviewpoint, though actually found to promote drying of paint films. Insome instances, bad discoloration limits the application of the driersto darker comparison of drier activity obtained by comparison withstandard films containing cobalt, lead and manganese driers.

It is obvious that more or less in quantity of the drier tested mayeffect the rate of dry within the limits of proportion herein defined.Above 2% of drier is not appreciably more effective than 1.75% and 2% istherefore an upper limit dictated by optimum performance.

Table.Cmparis0n of organic compounds used in place of lead driersComparison with Vehicle Compound substituted standard cobalt, lead andmanganese driers '2-ethyl hexaldehyde" Faster dry.

Cinnamic aldehyde.-. Do. Maleic-rosin-soya bean oil; oil length, 52%NVM; acid value, -12; viscosity-T 3,5,5-trimethyl hexaldehy Do.

(Gardner Hold Octa-decenyl aldehyde-.. Slightly slower.

n-Decyl aldehyde Do.

Pentaerythritol; phthalate-pentaerythritol; rosin linseed oil modifiedalkyd oil length, 56% NVM.

Pentaerythritol-phthalate; linseed-says. bean oil modification; oillength, 58%

N VM; acid value, 5-6; viscosity-X (Gardner Holdt).

Pentaerythritol-rosin linseed oil vehicle; oil length, 66% NVM; acidvalue, 3-6;

viscosity-I (Gardner Holdt).

Pentaerythritol-glycerine linseed-soya modification; oil length, 73% NVM; acid value, 3.6-7.2; viscosity-T (Gardner Hoidt).

(1.64% of above used) 'Octa-decenyl aldehyde Faster than standard.{Zethyl hexaldenyde Slightly slower.

(0.93% of above used) Z-ethyl hexzildebyde Faster. 3,5,5-trimethyihexaldehyde Do. n-Decyl aldehyde Slightly slower. Cinnamic aldehyde Do.

(0.735% of above used) Oeta-decenyl aldehyde (0.5% Faster.

of above used). 2-ethyl hexaldenyde. Faster. Octa-deeenyl aldehyde.Slightly slower.

(0.93% of above used) 2-ethyl hexaldenyde Slower.

(0.31% of above used) Among the non-metal containing organic compoundstests and found useful as having a similar function to the lead soaps asdriers in conjunction with the unsaturated fatty acid groups ofoleoresinous varnishes are the following:

Carbonyl compoundHliphazic aldehydes:

Octa-decenyl aldehyde 2-ethyi hexaldehyde n-Decyl aldehyde3,5,5-trimethyl hexaldehyde Citronnellal Cinnamic aldehyde Aninteresting result was observed in the comparison of certain of thearomatic ring compounds containing aldehydic substituents. Test resultsindicated that if the ring was substituted in the para position to thecarbonyl containing group with a phenolic group, outstanding drieractivity was obtained. When the hydroxy group was in a meta position theresults were not unusually good, but when that group as ortho inposition to the carbonyl containing group, improvement over the metasubstitucd compounds was observable. It was thus found that the firstdescribed substituents, e. g., a hydroxy group para to the carbonylcontaining group gave preferred results with ortho substituents secondin order. These compounds are described in copending application SerialNo. 147,334, filed March 2, 1950, now U. S. Patent No. 2,631,944, issuedMarch 17, 1953 of which this case is a division thereof.

For use of the above organic carbonyl compounds as driers it is mostconvenient that they be dissolved in organic solvents which are misciblewith the drying 011 containing vehicles into which they are to becompounded.

Of the useful aliphatic aldehydes most are fairly completely soluble inmineral spirits and varnish makers naphtha, and because of theirsolubility in a common solvent used in the paint and varnish makers arthave inherent advantage in respect to solubility.

While it is preferable that the driers to be prepared in concentratedform by dissolving the effective carbonyl compounds in suitable solventsprior to use, it is not essential to resort to this step as they mayalso be directly incorporated in the ranges useful in the coatingcompositions described.

In the table which follows, the general character of the test vehiclesare described in the first column. The second column lists the compoundswhich are found to have observable drier activity and the percentage oflead (as the metal) in the standard and the percentage of the purelyorganic drier compared therewith. In the last column observations arerecorded as to the result It has further been observed upon periodicexamination and testing of the vehicle-drier combinations described inthe table that in some instances an initially very high peak of drieractivity will level off to some extent. However, the change bycomparison with the compositions containing the lead driers and theidentical vehicles has been relatively insignificant and the aging testsso far indicate no instability problems due to the substitution of thedriers as indicated in the disclosure.

While the research leading to the discovery of the above describedpurely organic compounds was conducted with the idea in mind ofsubstitutions for lead soaps or driers in drying oil modified coatingcompositions, it is apparent that the compounds described need notnecessarily be used in conjunction with cobalt and manganese driers, butmay be used either alone or in combination with each other where it isexpedient to eliminate all metallic drier combinations. However, as ispreferable in the art today, combinations of driers will be founduseful.

Having described the invention, we claim:

1. A composition of matter which comprises in combination a siccativeorganic film forming coating composition containing drying oil fattyacid groups and a metal free drier catalyst, said drier selected fromthe group of aliphatic aldehydes consisting of Z-ethyl hexaldehyde,cinnamic aldehyde, 3,5,S-trimethyl hexaldehyde, octa-decenyl aldehyde,n-decyl aldehyde and citroneliai.

2. A drier catalyst in combination with an organic coating compositioncontaining drying oil fatty acid groups, said drier comprising 2-ethylhexaldehyde.

3. A drier catalyst in combination with an organic coating compositioncontaining drying oil fatty acid groups, said drier comprising cinnamicaldehyde.

4. A drier catalyst in combination with an organic coating compositioncontaining drying oil fatty acid groups, said drier comprising n-decylaldehyde.

5. A drier catalyst in combination with an organic coating compositioncontaining drying oil fatty acid groups, said drier comprisingoctadecenyl aldehyde.

6. A drier catalyst in combination with an organic coating compositioncontaining drying oil fatty acid groups, said drier comprisingcitronellal.

7. A composition of matter which comprises in combination a siccativeorganic film-forming coating composition containing drying oil fattyacid groups and as a drier catalyst therefor a metal free unsubstitutedaliphatic aldehyde containing from seven to eighteen carbon atoms.

8. A composition of matter which comprises in combination a siccativeorganic film-forming coating composition containing drying oil fattyacid groups and as a References Cited in the file of this patent NumberUNITED STATES PATENTS Name Date Koenig et a1 July-7, 1936 10 CuperySept. 28, 1943 6 OTHER REFERENCES Mattiello Protective and DecorativeCoatings, vol.

1, page 533.

Printing Inks, Ellis Reinbold Publishing Corporation.

Copyright, 1940, pages 109 and 110.

1. A COMPOSITION OF MATTER WHICH COMPRISES IN COMBINATION A SICCATIVEORGANIC FILM FORMING COATING COMPOSITION CONTAINING DRYING OIL FATTYACID GROUPS AND A METAL FREE DRIER CATALYST, SAID DRIER SELECTED FROMTHE GROUP OF ALIPHATIC ALDEHYDES CONSISTING OF 2-ETHYL HEXALDEHYDE,CINNAMIC ALDEHYDE, 3,5,5-TRIMETHYL HEXALDEHYDE, OCTA-DECENYL ALDEHYDE,N-DECYL ALDEHYDE AND CITRONELLAL.